However, the Athenians, distressed by the plague, and by the war that had recently broken out and was now raging, thought it a serious matter to add Lesbos with its fleet and untouched resources to the list of their enemies; and at first would not believe the charge, giving too much weight to their wish that it might not be true. But when an embassy which they sent had failed to persuade the Mitylenians to give up the union and preparations complained of, they became alarmed, and resolved to strike the first blow. They accordingly suddenly sent off forty ships that had been got ready to sail round Peloponnese, under the command of Cleippides, son of Deinias, and two others; word having been brought them of a festival in honour of the Malean Apollo outside the town, which is kept by the whole people of Mitylene, and at which, if haste were made, they might hope to take them by surprise. If this plan succeeded, well and good; if not, they were to order the Mitylenians to deliver up their ships and to pull down their walls, and if they did not obey, to declare war. The ships accordingly set out; the ten galleys, forming the contingent of the Mitylenians present with the fleet according to the terms of the alliance, being detained by the Athenians, and their crews placed in custody. However, the Mitylenians were informed of the expedition by a man who crossed from Athens to Euboea, and going overland to Geraestus, sailed from thence by a merchantman which he found on the point of putting to sea, and so arrived at Mitylene the third day after leaving Athens. The Mitylenians accordingly refrained from going out to the temple at Malea, and moreover barricaded and kept guard round the half-finished parts of their walls and harbours.

When the Athenians sailed in not long after and saw how things stood, the generals delivered their orders, and upon the Mitylenians refusing to obey, commenced hostilities. The Mitylenians, thus compelled to go to war without notice and unprepared, at first sailed out with their fleet and made some show of fighting, a little in front of the harbour; but being driven back by the Athenian ships, immediately offered to treat with the commanders, wishing, if possible, to get the ships away for the present upon any tolerable terms. The Athenian commanders accepted their offers, being themselves fearful that they might not be able to cope with the whole of Lesbos; and an armistice having been concluded, the Mitylenians sent to Athens one of the informers, already repentant of his conduct, and others with him, to try to persuade the Athenians of the innocence of their intentions and to get the fleet recalled. In the meantime, having no great hope of a favourable answer from Athens, they also sent off a galley with envoys to Lacedaemon, unobserved by the Athenian fleet which was anchored at Malea to the north of the town.